Electronic timer



Sept. 8, 1953 w. H. ESSELMAN ELECTRONIC TIMER Filed Nov. 19, 1949 O mwh 3.MV4 .m 0 m T I e -u m. w uou:o e g m S w) n w x m I o T 2 d v| .K 4 U m w U 7 omoso 4 Starter Station INVENTOR Walter H.Esselman.

WITNESSES: r %w A Z fMW ATTORN EY Patented Sept. 8, 1953 2,651,770 ELECTRONIC TIMER Walter H. Esselman, Cranford, N. J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 19, 1949, Serial N 0. 128,353

12 Claims.

This invention relates to electronic timers and it has particular relation to. electronic timers having a time delay which may be adjusted from a control station remote from the timer.

In. systems employing electronic timers it is sometimes desirable to control the time delay of the electronic timer from a remote control station. Any control circuit extending between the the conductors of the circuit and between the conductors and adjacent electroconductive masses. Although electronic timers controlled from a remote station have numerous applications, the timer herein described has been found particularly suitable for elevator systems and will be discussed with reference to such a system.

In an elevator system, equipment for controlling the operation of one or more elevator cars between the fioors of a building usually is located in a penthouse. The operation of the elevator cars when arranged in banks usually is supervised by a person or starter located on the street floor of the building. In tall buildings, the street floor is substantially displaced from the penthouse.

In order to permit the starter to control the performance of the elevator system, a starter station having suitable controls is located at the street floor in a location convenient to the starter. The controls of the starter station are connected to equipment in the penthouse through long circuits.

In accordance with the invention, an electronic timer is provided which may be located in the equipment station of an elevator system. The time interval of the timer may be adjusted from the starter station through a circuit which is insulated from the timer. In a preferred embodiment of the invention, the electronic timer has a time delay dependent on the time constant of a direct-current circuit. This time constant circuit provides a first bias on which the time delay of the timer is dependent. In order to control the time delay, an alternating-component bias is provided which is adjustable from the starter station. This alternating-component bias is introduced to the timer by means of a circuit extending between the equipment and starter stations. The circuit is electrically insulated from the timer. Consequently, changes in the electrical properties of the circuit cannot afiect conductively the timeconstant circuit employed in the timer. Preferably, the circuit extending between the equipment and starter stations is inductively coupled to the electronic timer.

It is, therefore, an object of the invention to provide an improved electronic timer which has a time interval adjustable from a remote station.

It is a further object of the invention to provide an electronic timer having an adjusting circuit associated therewith which is electrically insulated from the timer.

It is also an object of the invention to provide a timer having a direct-current time-constant circuit for determining the time interval of the timer in association with an alternating-current inductively coupled to the timer for the purpose of adding an alternating component to the timer energization.

It is an additional object of the invention to provide an elevator dispatcher having a timer controlled from a remote starter station through an electrical circuit which is electrically insulated from the timer.

Other objects of the invention will be apparent from the following discussion taken in conjunction with the accompanying drawing, in which:

Figure 1 is a schematic View with parts shown in elevation and parts broken away of an elevator system including an electronic timer embodying the invention, and

Figs. 2 and 3 are graphical representations showing the variation of certain voltages in the electronic timer of Fig. 1 with respect to time. 7 Referring to the drawing, Fig. 1 shows an elevator system for a building having a large number of floors. An elevator car I is shown at the street floor 3. This elevator is connected through one or more cables or ropes 5 to a sheave l which is located I in the equipment station 9. The equipment station 9 is in the penthouse of the building which is displaced by many floors 3a, 317, etc. from the first floor 3. The ropes or cables pass over the sheave l and are attached to a counterweight II. The sheave I is attached to a shaft I3 which is rotated by means of an electrical motor [5 and which is braked by means of a suitable brake [1.

Suitable control equipment is provided for controlling the operation of the motor l5 to start and stop the car I at desired fioors of the building. The control equipment is represented in part by a conventional selector 18 which is driven fromthe shaft I3 in accordance with movements of the car I. A car switch 19 may be provided in the car i for the purpose of initiating a starting or stopping operation of the elevator car. Inasmuch as the equipment for starting and stopping the elevator car may be of conventional construction, a more detailed description thereof is believed unnecessary for an understanding of the invention. As representative of suitable elevator systems, reference may be made to the Eames Patent 2,447,925. It will be understood that a number of elevator cars, all similar to the car I, may be installed for operation in the building in the same manner. For example, a car la is shown in Fig. 1 for operation in a bank with the car I.

For eflicient operation, it is desirable that the elevator cars of the bank :be dispatched from terminal or dispatching floors in accordance with a predetermined schedule or plan. It is "common practice in the art to provide a dispatcher which initially notifies a car attendant that his car will be the next car to leave a dispatching floor and which thereafter notifies the car attendant, by a suitable signal, that he is to leave or start from the dispatching floor. An electronic timer 2| suitable for establishing intervals between successive departures of cars from a dispatching floor is located in the penthouse or equipment station.

The electronic timer 21 includes an electronic discharge device 23. This device may be of any suitable construction capable of providing a controlled electrical discharge. As examples of suitable electronic discharge devices, reference may be made to high-vacuum, grid-controlled electronic tubes, gaseous grid-controlled tubes, and transistors. The grid-controlled gaseous-discharge tubes which are known as thy-ratrons are particularly suitable 'for the electronic timer and it will be assumed that such a tube is here employed.

The tube 23 has main electrodes in the form of an'anode 23a and a cathode 230 between which an electrical discharge may be established. A heater 23h is energized from a suitable source of electrical current (not shown) for the purpose of heating the cathode 23c. -A control electrode or grid 239 is associated with the main electrodes for the purpose of controlling the initiation of a discharge therebetween. In a suitable voltage is applied between the main electrodes and if a suitable voltage is applied to the grid 23g relative to one of the main electrodes, a discharge will be initiated between the main electrodes. Inasmuch as the tube 23 is assumed to be a thyratron, it will be understood that once a discharge is initiated between the main electrode, the grid 23g loses control of the discharge and other means must be provided for terminating the discharge. It will be assumed that the tube 23 requires the grid 23g to be at a substantial positive potential relative to the cathode in order to initiate a discharge between the main electrodes.

Energy for the electronic timer is supplied by two buses L+ and L- which are connected to a suitable direct current source of electrical energy through switches 25. The main electrodes are connected across the conductors L+ and L- through make contacts Al of a relay A and through the operating winding of a relay B.

A control or grid circuit is provided for the grid 239 which may be traced from the grid through a resistor RI, a capacitor C, a winding 21 and the bus L, to the cathode 230. The voltage between the grid 23y and the cathode 23c 4 is determined essentially by the voltages across the capacitor C and the winding 21.

The capacitor C is charged from the buses L+ and L- through a series circuit which includes the capacitor, the winding 21 and a currentlimiting resistor R2. Inasmuch as the winding 21 generally has a negligible resistance, the rate of charge of the capacitor C is determined substantially by the capacitance of the capacitor and the resistance of the resistor R2. The resistor R2 and the capacitor C consequently constitute what is usually referred to as a time constant or RC circuit. The resistor R2 may be adjustable if desired, for the purpose of adjusting the time constant of the RC circuit. However, for most applications, a fixed resistor R2 may be employed and adjustment of the time interval of the electronic timer may be adjusted in a manner hereinafter described.

The capacitor C may be discharged through a shunt circuit completed by break contacts A2 of the relay A. If desired, the shunt circuit may contain substantially no resistance. Preferably, a resistor R3 having a low value of resistance included in the shunt circuit for the purpose of preventing an excessive how of current therethrough.

When a discharge is initiated in the tube 23, the resulting flow "of current :may be employed .for

any desired control or signaling operation. In

the embodiment of Fig. 1 a discharge in the tube 23 results in pickup of the relay 35. Upon -picking up, the relay B closes its make contacts :BI to connect a start lamp 31 across the .buses and L.. Illumination .of the lamp 31 indicates to the car attendants that .a scar vis to leave the dispatching floor. .As well understood in the cart, suitable mechanism may be'provid'ed for thelpnrpose of indicating which 'of the cars is to be the next car to leave the dispatching zfloor. .Hew, ever it will be assumed 'here that cars will leave the dispatching floor in response to the start lamp 31 in accordance with a predetermined plan.

A timing interval is initiated by energization of the relay A. This relay is energized by a cir- -cuit which may be traced from the bus L+ through the operating winding of the relay A, a switch 33 and a switch 35 to the bus L-.. The switch '38 is a manually-operable switch which when closed shunts break contacts B2 of the relay B. Theswitch 35 is intended to be operated as each car starts from the dispatching floor. The switch 35 usually would be automatically operated by the departure of each elevator car from the dispatching floor. However, for present purposes, 'it will be assumed that each elevator attendant in leaving the dispatching floor presses and releases the normally-closed push-button switch 35.

Murder to adjust the interval of the electronic timer from the remote or starter station located on the street floor '3 of the'building, a circuit 31 is provided which extends between the equipment station in the penthouse and the starter station. This circuit is electrically insulated from the timer but is inductively coupled thereto by means of a winding 38. The windings 38 and 21 :are mutually coupled and form in effect the primary and secondary windings of a transformer.

The circuit 31 is connected to a suitable voltage divider located in the starter station. This voltage divider 'is adjustable and may be of :any

desired construction, such as an adjustable autotransformer. It will be assumed for present purposes that the voltage divider is formed by a resistor 39 which is connected for energization from a suitable alternating current source AC through a switch 41. The alternating current source may be the conventional, stable, 60 cycle, 120 volt source commonly employed to supply lighting to the building. The resistor 39 has an adjustable tap 39a associated therewith. The circuit 31 is connected to one terminal of the resistor and to the adjustable tap. Consequently, the voltage applied to the circuit 31 has a magnitude dependent on the position of the adjustable tap 39a. The position of the tap is under the control of the starter.

It is believed that the operation of the electronic timer now may be set forth. To place the electronic timer into operation, the switch 4! is closed to connect the alternating current source to the resistor 39. In addition, the switches 25 are closed to connect the buses L+ and L- to a direct current source.

Inasmuch as the contacts A2 have been closed, the capacitor C is in a discharged condition. Upon closure of the switches 25, an energizing circuit for the relay A is established as follows:

L+, A, 33, 35, L

As a result of its energization, the relay A closes its contacts Al to complete the connection of the main electrodes 23a and 230 of the tube across the buses L+ and L. However, no discharge results from such connection of the main electrodes for the reason that the control electrode 23g and the cathode 230 are substantialy at the same potential.

The relay A also opens its break contacts A2 to interrupt the shunt circuit around the capacitor C. The cayacitor now starts to charge from the buses L+ and L- at a rate determined by the time constant of the capacitor and the resistor R2. At the same time, an alternating voltage is induced in the winding 21 which has a magnitude dependent on the adjustment of the tap 39a at the starter station. The relationships of the various voltages are illustrated in Fig. 2.

In Fig. 2 ordinates represent voltage and abscissae represent time. The breakdown or firing voltage between the control electrode 239 and the cathode 23c necessary to initiate a discharge between the main electrodes of the tube 23 is represented in Fig. 2 by a dotted line 43. When the capacitor starts to charge, the voltage thereacross follows the line 45 of Fig. 2. By inspection of Fig. 2 it will be observed that the voltage across the capacitor slowly increases towards the value required to initiate a discharge in the tube 23.

The alternating voltage introduced by the winding 21 into the grid control circuit is represented in Fig. 2 by a curve 41 which is shown superimposed on the curve 45. It should be noted that the amplitude of this curve 41 is insufficient to provide by itself the breakdown voltage represented by the line 43.

. The voltage actually applied between the grid 23g and the cathode 23c of the tube 23 is dependent on the resultant of the voltages represented by the curves 45 and 41 of Fig. 2. When this resultant intersects the line 43 at the time TI, the voltage between the grid 23g and the cathode 23c becomes sufficient to initiate a discharge in the tube 23, and the relay B promptly is energized and picks up. Since the tube 23 is a thyratron, the grid now loses control of th discharge.

In response to closure of the'make contacts Bl, the start lamp 3| is illuminated to indicate that a car is to leave the dispatching floor. The attendant of the next car to leave the dispatching floor actuates the switch 35 to interrupt the energizing circuit for the relay A. This relay consequently closes its break contacts A2 to establish a shunt circuit for the capacitor C and the capacitor promptly discharges. In addition, the contacts Al open to interrupt the discharge through the tube 23. The resulting deenergization of the relay B results in opening of the contacts Bi to extinguish the lamp 3 l Upon release of the switch 35 by the car attendant the relay A again is energized. Consequently, the make contacts Al reclose to connect the main electrodes of the tube 23 across the associated buses L+ and L. However, the capacitor C now is in a discharged condition and the grid voltage of the tube 23 is insufiicient to initiate a discharge between the main electrodes.

The energization of the relay A also results in opening of the break contacts A2 to interrupt the discharge circuit for the capacitor C. The capacitor C now starts to charge and the voltage thereacross builds up in accordance with the curve 45 of Fig. 2. After the lapse of the time Tl from the reclosure of the switch 35, the voltage between the grid and the cathode of the tube 23 again becomes suflicient to initiate a discharge therein. The resulting reillumination of the lamp 3! indicates that another car is to start from the dispatching floor. The foregoing cycle is repeated indefinitely and the cars are successively started after the expiration of a minimum interval represented by the time TI.

If because of changing trafiic conditions the starter desires to increase the dispatching interval, he rotates the tap 39a at the starter station in a clockwise direction as viewed in Fig. 1. This reduces the voltage induced in the winding 21 in magnitude to a Value represented by the curve 41a which is shown superimposed on the curve 45 in Fig. 3. When the capacitor C starts to charge, it now requires a time represented by the line T2 of Fig. 3 before the resultant of the capacitor voltag represented by the curve 45 of Fig. 3 and the winding voltage represented by the curve 41a of Fig. 3 becomes sufficient to intersect the breakdown voltage line :33 and initiate a discharge in the tube 23. Consequently, the dispatching interval has been increased from the time Tl of Fig. 2 to the time T2 of Fig. 3 as a result of the adjustment of the tap 39a by the starter. By suitable adjustment of the tap 39a, the starter can select any desired minimum dispatching interval within the range of the electronic timer.

Inasmuch as the circuit 31 is completely insulated from the time constant circuit associated with the tube 23, variations in resistance of the long circuit 31 or in the leakage resistance between conductors 31 or in the capacitance between the conductors or between each conductor and associated electroconductive masses have substantially no effect on the timeconstant circuit.

If completely automatic operation of the timer at regular intervals is desired, the switch 33 may be opened to place the energization of the relay A under control of the break contacts B2 of the relay B. When the timer initially is energized as a result of closure of the switches 25 and 4|, the following circuit is effective for energizing the relay A:

As previously pointed out, energizationof the relay A starts a timing cycle which results in firing of the tube 23 and energization of the relay B.

The energized relay 3 closes its contacts Bl to illuminate the lamp 3]. Also, contacts 132 open to interrupt the energization of the relay A.

Deenergization of the relay Aresults in closure of the contacts A2, to discharge the capacitor C, and in opening of the contacts Al to interrupt the discharge in the tube 23.

When the discharge in the tube is interrupted, the relay B is deenergized and opens its make contacts Bl to extinguish the lamp 3|. Also, the contacts B2 are closed to reenergize the relay A, thus initiating another timing cycle. As a result of the repeated, timing cycles, the lamp flashes briefly at regular time intervals. The duration, of the time intervals between flashes of the lamp may be controlled by the setting of the adjustable tap 39a.

In this discussion of automatic operation, it is assumed that the contacts Bl are make contacts. If the contacts Bi were break contacts, the lamp 31 would be illuminated during each timing interval and would be extinguished briefly at the end of each of the timing intervals,

Although the invention has been described with reference to certain specific embodiments thereof, numerous modifications falling within the spirit and scope of the invention are possible.

I claim as my invention:

1. In an elevator system for a multi-floor building having an equipment station for equipment employed in theelevator system ,and a control station displaced by a plurality of floors from the equipment station, an elevator dispatcher comprising an electronic timer disposed in the equipmentv station, said timer including an electronic discharge device capable of having a discharge produced therein, dispatching means re sponsive to a discharge in the discharge device, and means adj ustably controlling the intervals between discharges in said discharge device, said last-named means comprising a source of alternating current, a circuit extending between said stations for conducting an alternating quantity from the source to the timer, and an adjuster located at the control station for adjusting the value of the alternating quantity supplied by the source to the timer, and means responsive to said alternating quantity for controlling the interval between discharges in the discharge device, the connections of said circuit extending between the stations being insulated from the discharge device.

2. A system as claimed in claim 1 wherein the timer includes a source of direct voltage for producing a discharge in the discharge device.

3. A system as claimed in claim 1 wherein said circuit includes a first winding energized from the source under the control of said adjuster, said timer having a second winding in.- ductively coupled to the first winding, said windings being located adjacent said .discharge device.

4, A system as claimed in claim 1. wherein the timer includes direct current means insulated from said connections for providing a gradually varying direct quantity, and means responsive to the resultant of the direct and alternating quantities for initiating a discharge in the discharge device.

5. In an electronic timer, an electronic discharge device having a discharge path and control means for controlling the production of a discharge in said initiation means, a control circuit for, energizing the control means to produce said discharge a predetermined. timer after an operation ofv the initiation means, and adjustable means for adjusting the energization oi the control means, said adjustable means being electrically insulated from the control means, whereby variations in the electrical properties of. the adjustable means do not by electrical conduetion affect the control means, said control circuit including direct-current means for applying to the. control means a direct quantity which. varies in magnitude as a function of time, and said adjustable means comprising means for applying an adjustable alternating quantity to the control means, the discharge of the; discharge device being controlled by the resultant of; the direct and; alternating quantities. V

6. In an electronic timer, any electronic dis.- charge tube having a pair of main electrodes between which an electrical discharge may be produced and acontrol electrode for controlling the discharge between the, main electrodes, a control circuit including a capacitor for biasing the controlv electrode relative: to at least. one of the main electrodes with a bias which varies as a function of time for controlling the production of a. discharge in the tube when the main electrodes are connected, toa suitable source of energy, the biasing being responsive to. the voltage of the capacitor, direct-current means for charging the capacitor to provide a direct voltage across the terminals. of, the. capacitor, means for discharging the capacitor, and adjustable means for adjusting said biasing, the adjustable means comprising anadjustable source of alternating voltage inductively coupled tothe control circuit to make said biasing dependent on the resultant of the direct voltage and the alternating voltage.

7,. An electronic timer as claimed in claim 6 wherein the. discharge. tube, is a gaseous tube wherein the control electrode loses control of the discharge between the main electrodes. once the discharge starts, the direct-current means for charging, the capacitor comprising a currentlimiting resistor and a winding connected in a series circuit with the capacitor Ior energization fromasource of, direct current. d'said'adjjustable means include a winding inductively coupled to, and insulated from, the first-named winding, whereby the adjustable. source of alternating voltage cannot conductively effect the time constant of, the; series circuit, and means for interrupting a discharge between the main electrodes.

8. An electronic timer as claimed in claim 6 in combination with a source of direct voltage connected to saidmain electrodes for establishing across saidv main. electrodes, a discharge, initiated by said bias, whereby the timing of said discharge varies as a, continuous function, of said resultant,

9. In a control system, an equipment station, an. electronic discharge device located at the equipment station and capable of having a discharge produced therein, said di r device having electrically-energizable discharge control means for controlling the formation of a, discharge in the discharge device, a control. station spaced from the equipment station, and means adjustably controlling from the control station the discharges in said discharge device, said lastnamecl means comprising an adjuster located at the control station, a source of alternating energization, .a coupling unit located adjacent the equipment station, and a circuit extending be:-

9 tween the stations for transmitting an alternating quantity controlled by the adjuster from the source to the coupling unit for energizing the discharge control means, said coupling unit comprising means for effectively coupling the circuit to the discharge device through an insulated path.

10. In a control system, an equipment station, an electronic discharge device located at the equipment station and capable of having a discharge produced therein, said discharge device having in an evacuated vessel main electrodes between which a discharge may be produced and having electrically-energizable discharge control means for controlling the formation of a discharge between the main electrodes, a control station spaced from the equipment station, and means adjustably controlling from the control station the discharges in said discharge device, said last-named means comprising an adjuster located at the control station, a source of alternating energization, a transformer located adjacent the equipment station, and a circuit extending between the stations for transmitting an alternating quantity controlled by the adjuster from the source to the transformer for energizing the discharge control means, said transformer comprising means for effectively coupling the circuitto the discharge device through an insulated path.

11. In a control system, an electronic tube having main electrodes between which a discharge may be passed and having a control electrode for controlling the production of a discharge between the main electrodes, initiation means operable from a first to a second condition, a control circuit for conditioning the control electrode to produce a discharge between the main electrodes a predetermined time after an operation of the initiation means, and adjustable means for adjusting the conditioning of the control electrode to vary said predetermined time, said adjustable means being electrically insulated to prevent application of a potential difference by conduction 10 therefrom to the control circuit, whereby varia-* tions in the electrical properties of the adjustable means do not by electrical conduction affect the control means.

12. In a control system, an electronic tube having main electrodes between which a discharge may be passed and having a control electrode for controlling the production of a discharge between the main electrodes initiation means operable from a first to a second condition, a control circuit for conditioning the control electrode to produce a discharge between the main electrodes a predetermined time after an operation of the initiation means, and adjustable means for adjusting the conditioning of the control electrode to vary said predetermined time, said adjustable means being electrically insulated to prevent application of a potential difierence by conduction therefrom to the control circuit, whereby variations in the electrical properties of the adjustable means do not by electrical conduction affect the control means, said adjustable means comprising a remote control station displaced substantially from the discharge tube, an adjuster positioned at the remote control station for effecting said adjusting of the energization of the control means, and translating means responsive to a discharge between said main electrodes.

WALTER H. ESSELMAN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,892,017 Stansbury Dec. 27, 1932 2,067,378 Chubbs Jan. 12, 1937 2,132,264 King Oct. 4, 1938 2,177,400 Almquist Oct. 24, 1939 2,371,981 Few Mar. 20, 1945 2,425,047 Reeves Aug. 5, 1948 FOREIGN PATENTS Number Country Date 487,982 Great Britain June 29, 1938 

